Prusky, D., Department of Plant Pathology, University of California, Riverside, 92521, United States
Gold, S., Department of Plant Pathology, University of California, Riverside, 92521, United States
Keen, N.T., Department of Plant Pathology, University of California, Riverside, 92521, United States
Gold, S., Department of Plant Pathology, University of California, Riverside, 92521, United States
Keen, N.T., Department of Plant Pathology, University of California, Riverside, 92521, United States
An endopolygalacturonase from C. gloeosporioides was purified 130-fold to apparent homogeneity using phenyl sepharose chromatography followed by isoelectric focusing. The purified preparations contained two polygalacturonase species of 68 and 62 kD based on SDS gel electrophoresis and thin layer gel electrofocusing. These apeared to be glycosylation adducts of a single protein since their amino acid composition and N-terminal amino acid sequences were identical and treatment with endoglycosidase F altered their migration to yield a single band on SDS gel electrophoresis. The purified C. gloeosporioides endopolygalacturonase efficiently macerated avocado and cucumber tissue. Epicatechin at 20 and 80 μg ml-1 inhibited enzyme activity by 6.5% and 43%, respectively. The concentration of epicatechin in peel of unripe avocado fruits ranged between 430-1970 μg g-1 fr wt (570-2600 μg ml-1) but decreased in ripe susceptible fruits to 6-25 μg g-1 fr wt (approx. 8-30 μg ml-1). These observations raised the possibility that epicatechin might regulate the activity of the fungal endopolygalacturonase in infected avocado fruits. © 1989.
